Hemotropic mycoplasmas (hemoplasmas) are epierythrocytic parasites that are associated with clinical disease in dogs and cats. The major canine hemoplasmas include Mycoplasma haemocanis and Candidatus Mycoplasma haematoparvum. Most canine hemoplasma infections are latent, and clinical disease is typically associated with immunosuppression, splenectomy, and other coinfections. The Rhipicephalus sanguineus tick is a proposed vector for canine hemoplasmas. A previous European study found 15% hemoplasma-positive dogs on polymerase chain reaction (PCR) in an area in southern France that had an established R sanguineus population. This study examined canine hemoplasma prevalence in a Swiss region in which R sanguineus occurrence was rare. Blood samples were collected from 889 dogs over a 1-year period from the Clinic for Small Animals at the University of Zurich. Both healthy and sick dogs were included. Total nucleic acids were extracted from each sample, and real-time PCR was performed for M haemocanis and Candidatus Mycoplasma haematoparvum. The positive rate was 1.2%. There were no dual infections, and infection was not significantly associated with anemia, gender, or age. Follow-up samples from infected dogs were persistently positive. Phylogenetic analysis on 4 positive samples revealed greater than 99.8% relatedness to published hemoplasma sequences. Most infected dogs had traveled to or from diverse countries outside of Switzerland. No infected dogs had clinical signs of hemoplasmosis.

COMMENTARY: This is a very interesting study on the presence of hemoplasmas in a European canine population. Clinical hemoplasma infection in dogs is rarely seen in nonenzootic areas, and pets typically display clinical signs in the presence of comorbidities. This study suggests that veterinarians should be aware of hemoplasma infection in dogs. It also supports the association between travel and infection status and identifies the spread of emerging infectious diseases to nonenzootic areas. The R sanguineus tick is located throughout the United States, and as the presumptive vector of the most common canine hemoplasmas, may contribute to their U.S. prevalence.

Real-time PCR-based prevalence study, infection follow-up and molecular characterization of canine hemotropic mycoplasmas. Wengi N, Willi B, Boretti FS, et al. VET MICROBIOL 126:132-141, 2008.